Initiate fluid replacement therapy in a patient with hyperosmolar hyperglycaemic state (HHS) by first assessing the degree of dehydration and shock. If shock is suspected, start with rapid intravenous infusion of 0.9% sodium chloride at 10 ml/kg to restore circulatory volume.
Once shock is corrected or if shock is not present, begin rehydration with isotonic fluids such as 0.9% sodium chloride, adjusting the volume based on the estimated fluid deficit and maintenance requirements.
Monitor plasma electrolytes (sodium, potassium), urea, creatinine, and glucose regularly, and adjust fluid composition accordingly.
Potassium supplementation should be considered once plasma potassium is known, as hypokalaemia can develop during treatment.
In hyperosmolar states, avoid rapid correction of sodium to prevent cerebral oedema; the rate of plasma sodium change should not exceed 12 mmol/l in 24 hours.